Phototelegraphic transmitting plate



Nov. 10, 1925 M. FERREE ET AL PHOTOTELEGRAPHIC TRANSMITTING PLATE Filed Jan. 1, 1925 Wvavroas I Patented Nov. 10, 19 25.-

NITED PATIEN oFFicE.

' MARVIN rnnnnn, oRNEw'YoR N.

A CORPORATION "or NEW YORK.

a v I AND zrosnrnf wrssivmn; or QLEVELAND, onro, ASSIGNORS ro-PACIFIC AND ATLANT C rumo s, me, or NEW ORK, Y.,

rnoro'rnnnenarn'ro TnANsMIT'rING PLATE.

Application file'd January 31, 1925. serial No. 5,954.

To all whom. it'may concern:

Be itkiiown that we, Marvin Fisuniiis and JOSEPH *"issnriin. citizens of the United ic Transmittin Plates.

States, residing in the citycounty, and State of New York, and in the city of Cleveland, county of 'Cuyahoga, and State of ()hio,'respectively, have invented cert '11 new and useful Improvements in Phototelegraphg I oi which the following is a specification. v

This invention relates to anew and useful improvement in making broken toneplates 1 for use in transmitting pictures by a series of electrical pulses.

It has been known to make. a bi'okeii' toiie duplicate of a picture by means of a series of'spaced dots, these ,dots being emu-posed of insulating material, and being arranged upon a conductiveplate. By connecting the conductive plate to one terminal'oi a source of electricity, and by connecting the other terminal of said source of. electricity. to a needle having a fine point, the circuit was made and broken .as the needle and plate were moved relatively to each other.

Pictures transmitted by the use of a Qbrokeii tone plate made as before described.

were often coarse because oftlie grained effect-so that the reproduction was 'lli'fQIlOl.

According to this invention. the broken.

tone picture consistsoi aseries of lines which are preferably parallel andwhicli are of varying width. These lines are composed of insulating material located upon a plate made of copper. or other material which will conduct electricity.

The drawing shows a preferred embodiment of this invention. a

The picture to be reproduced is placed. in front of an ordinary camera so that a negative can be made thereof; This "negative is made upon an ordinary transparent glass plate either wet or dry. Before the negative impression is made, a transparent grating having a series of parallel opaque lines thereon is placed in'the camera before the negative so that the negative image consists ofa series of parallel opaque lines of varying thickness and the continu ous tone of the picture to be reproduced 1s.

thus duplicated in what may be called broken tone.

The spacing of the opaque lines may vary and we do not wish to limit ourselves to any part cular spacing but we have'foun-d that a grating having sixty-five linestothe inch is satisfactory for-reproducing ordinau' photographsf The thickness of the said opaque lines may be equal to the distances between them but we'donot wish to limit ourselves to any particulartype 'ofgratingL "KVe have cording to our process avoids the coarse.

pattern effect produced when the negative is taken through a grating having cross lines. Wepreferto have the opaque lines of. "the grating held horizontally when the negative is taken. The negative thus produced is now usedfor making an enlarged positive'by means of an ordinary camera. We, prefer to make this positive twice as large as the negative of the original picture. .This enlargement enables a superior transmitting plate to be reproduced; The enlarged positive thus produced is now-printed upon a thin plate made of copperor other suitablebendable metal by means of anordinary printing frame. This metal plate which may be called the transmitting plate is coated with a sensitive film com-- prising fish glue, ammonium bichromate and white of eggs. This coating is made of sixteen ounces of fish glue, one ounce of" ammonium bichromate, six egg whites and either seventeen or thirty-four ounces of Water. These ingredients are thoroughly mixed and they aresprea'd upon the highly,

polished surface of thecopper plate. This coating is then dried, in which condition it is not very sensitive to daylightbut is sufiiciently sensitive to a powerful are light used for printing thereon from the enlarged positive. After the copper late has been exposed, it is washed in cod water until the portions of the coating which have not been until the adhering coating has been trans- I formed into a hard enameLIike material.

After the enamel has been formed, the plate iscleaned by rubbing it with a mixture of acetic acid and salt' as this eats away any of the coating which does not correspond to the image so as to produce clean bright copper lines between parallel lines of enamel of V9. ing width.

he plate thus formed can now be bent ifdesired so that it now-has a c lindrical shape and the bent plate-can now e placed u on the drum of a transmitting machine 0 an ordinary and well-known type.

.A device of the type in which this plate is adapted to be used is shown in; U. S. Pat ent No. 1,529, 17 3.

A preferred embodiment of this invention 5 has been described but it is clear that nu- I plateis developed in the ordinar manner,

merous changes and omissions could be made without departing from its spirit.

Experience'has'shown that if the metal then the portions or strips of tie copper plate intermediate the lines of insulating.

material are not clean and bright, because some of the nsulating material remains-on said stri s. 'By treatlng the developed and baked p ate .with a weak acid, such as acetic acid, and with a mild abrasive, such as particles of salt, the undeveloped portion of the coating is effectually removed. This results in'the production of aclear picture, without any noticeable pattern or grain.

graphic Claims:

1. A phototelegraphic transmission plate made of metal, said metal plate having thereon a broken tone reproduction of the picture to be electrically, transmitted, the said broken tone reproductioncom risinga series of parallel lines of varying t ickness, the said linesbeing composed of hard insulating material, that portion of the copper plate intermediate the said lines of insulatin material being free from the said insulatlng material.

phototele- 2. 'A method of making a fplate for transmitting pictures by means 0 a series of electrical pulses which consists in making a negative of a picture to bereproduced through a transparent grating having a' series of parallel opaque lines thereon so that the negative image thus formed has a series of parallel opaque lines of varying thickness, then making a positive from thesaid negative thus produced,

' then printing with the said positive upon a coating of light sensitive glue located 011 a metal plate, then developing the said coatmg so as to wash away the portions which have not been acted upon by the light, then baking the said coating so as to harden it and then removing any of the said coating which does not correspond to the image.

3. A method according to claim 2 in which the surplus coating is removed by rubbing the coating with a mixture of acetic acid and salt. I

4. A method according to claim 2 which consists'in removing the surplus coating by washing it With a weak acid and a mild abrasive. g

In testimony whereof we hereunto affix our signatures.

MARVIN FERREE. JOSEPH WISSMAR. 

